Cooling circuit for a multi-wall blade

ABSTRACT

A cooling system according to an embodiment includes: a serpentine cooling circuit, the serpentine cooling circuit including a first leg extending in a first direction, a second leg extending in a second direction, and a turn fluidly coupling the first leg and the second leg; and an air feed cavity for supplying cooling air to the serpentine cooling circuit; wherein the first leg of the serpentine cooling circuit extends radially outward from and at least partially covers at least one central plenum of a multi-wall blade, and wherein the second leg of the serpentine cooling circuit extends radially outward from and at least partially covers a first set of near wall cooling channels of the multi-wall blade.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to co-pending U.S. application Ser. Nos.:______, GE docket numbers 282168-1, 282169-1, 282171-1, 282174-1,283464-1, 283467-1, 283463-1, and 284160-1, all filed on ______.

BACKGROUND OF THE INVENTION

The disclosure relates generally to turbine systems, and moreparticularly, to a cooling circuit for a tip area of a multi-wall blade.

Gas turbine systems are one example of turbomachines widely utilized infields such as power generation. A conventional gas turbine systemincludes a compressor section, a combustor section, and a turbinesection. During operation of a gas turbine system, various components inthe system, such as turbine blades, are subjected to high temperatureflows, which can cause the components to fail. Since higher temperatureflows generally result in increased performance, efficiency, and poweroutput of a gas turbine system, it is advantageous to cool thecomponents that are subjected to high temperature flows to allow the gasturbine system to operate at increased temperatures.

Turbine blades typically contain an intricate maze of internal coolingchannels. Cooling air provided by, for example, a compressor of a gasturbine system may be passed through the internal cooling channels tocool the turbine blades.

Multi-wall turbine blade cooling systems may include internal near wallcooling circuits. Such near wall cooling circuits may include, forexample, near wall cooling channels adjacent the outside walls of amulti-wall blade. The near wall cooling channels are typically small,requiring less cooling flow, still.

maintaining enough velocity for effective cooling to occur. Other,typically larger, low cooling effectiveness internal channels of amulti-wall blade may be used as a. source of cooling air and may be usedin one or more reuse circuits to collect and reroute “spent” coolingflow for redistribution to lower heat load regions of the multi-wallblade. At the tip of a multi-wall blade, the near wall cooling channelsand low cooling effectiveness internal channels are exposed to very highheat loads.

BRIEF DESCRIPTION OF THE INVENTION

A first aspect of the disclosure provides a cooling system including: aserpentine cooling circuit, the serpentine cooling circuit including afirst leg extending in a first direction, a second leg extending in asecond direction, and a turn fluidly coupling the first leg and thesecond leg; and an air feed cavity for supplying cooling air to theserpentine cooling circuit; wherein the first leg of the serpentinecooling circuit extends radially outward from and at least partiallycovers at least one central plenum of a multi-wall blade, and whereinthe second leg of the serpentine cooling circuit extends radiallyoutward from and at least partially covers a first set of near wallcooling channels of the multi-wall blade.

A second aspect of the disclosure provides a multi-wall turbine blade,including: a cooling system disposed within the multi-wall turbineblade, the cooling system including: a serpentine cooling circuit, theserpentine cooling circuit including a first leg extending in a firstdirection, a second leg extending in a second direction, and a turnfluidly coupling the first leg and the second leg; and an air feedcavity for supplying cooling air to the serpentine cooling circuit;wherein the first leg of the serpentine cooling circuit extends radiallyoutward from and at least partially covers at least one central plenumof the multi-wall turbine blade, and wherein the second leg of theserpentine cooling circuit extends radially outward from and at leastpartially covers a first set of near wall cooling channels of themulti-wall turbine blade.

A third aspect of the disclosure provides a turbomachine, including: agas turbine system including a compressor component, a combustorcomponent, and a turbine component, the turbine component including aplurality of turbine buckets, and wherein at least one of the turbinebuckets includes a multi-wall blade; and a cooling system disposedwithin the multi-wall blade, the cooling system including: a serpentinecooling circuit, the serpentine cooling circuit including a first legextending in a first direction and a second leg extending in a seconddirection; and an air feed cavity for supplying cooling air to theserpentine cooling circuit; wherein the first leg of the serpentinecooling circuit extends radially outward from and at least partiallycovers at least one central plenum of the multi-wall blade, and whereinthe second leg of the serpentine cooling circuit extends radiallyoutward from and at least partially covers a first set of near wallcooling channels of the multi-wall blade.

The illustrative aspects of the present disclosure solve the problemsherein described and/or other problems not discussed.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of this disclosure will be more readilyunderstood from the following detailed description of the variousaspects of the disclosure taken in conjunction with the accompanyingdrawings that depict various embodiments of the disclosure.

FIG. 1 shows a perspective view of a turbine bucket including amulti-wall blade according to embodiments.

FIG. 2 is a cross-sectional view of the multi-wall blade of FIG. 1,taken along line A-A in FIG. 1 according to various embodiments.

FIG. 3 is a cross-sectional view of a tip area of the multi-wall bladeof FIG. 1, taken along line B-B in FIG. 1 according to variousembodiments.

FIG. 4 is a cross-sectional view of a tip area of the multi-wall bladeof FIG. 1, taken along line B-B in FIG. 1 according to variousembodiments.

FIG. 5 is a cross-sectional view of a tip area of the multi-wall bladeof FIG. 1, taken along line B-B in FIG. 1 according to variousembodiments.

FIGS. 6-8 depict an illustrative method for forming a portion of atwo-pass serpentine cooling circuit according to various embodiments.

FIG. 9 is a schematic diagram of a gas turbine system according tovarious embodiments.

It is noted that the drawing of the disclosure is not to scale. Thedrawing is intended to depict only typical aspects of the disclosure,and therefore should not be considered as limiting the scope of thedisclosure. In the drawing, like numbering represents like elementsbetween the drawings.

DETAILED DESCRIPTION OF THE INVENTION

In the Figures, for example in FIG. 9, the “A” axis represents an axialorientation. As used herein, the terms “axial” and/or “axially” refer tothe relative position/direction of objects along axis A, which issubstantially parallel with the axis of rotation of the turbomachine (inparticular, the rotor section). As further used herein, the terms“radial” and/or “radially” refer to the relative position/direction ofobjects along an axis (r), which is substantially perpendicular withaxis A and intersects axis A at only one location. Additionally, theterms “circumferential” and/or “circumferentially” refer to the relativeposition/direction of objects along a circumference (c) which surroundsaxis A but does not intersect the axis A at any location.

As indicated above, the disclosure relates generally to turbine systems,and more particularly, to a cooling circuit for cooling a tip area of amulti-wall blade.

According to embodiments, the cooling circuit is configured to cool thetip area of a multi-wall blade of a gas turbine engine, while providingshielding to low cooling effectiveness internal channels and providingcooling film. Shielding may also be provided to high coolingeffectiveness near wall cooling channels. The cooling circuit mayinclude a two-pass serpentine cooling circuit, which may be fed withcooling air from low cooling effectiveness internal channel or a nearwall cooling channel. Air passes through the cooling circuit, providingconvention cooling, and is exhausted as cooling film to cool the tiparea of the multi-wall blade.

Turning to FIG. 1, a perspective view of a turbine bucket 2 is shown.The turbine bucket 2 includes a shank 4 and a multi-wall blade 6 coupledto and extending radially outward from the shank 4. The multi-wall blade6 includes a pressure side 8, an opposed suction side 10, and a tip area12. The multi-wall blade 6 further includes a leading edge 14 betweenthe pressure side 8 and the suction side 10, as well as a trailing edge16 between the pressure side 8 and the suction side 10 on a sideopposing the leading edge 14.

The shank 4 and multi-wall blade 6 may each be formed of one or moremetals (e.g., steel, alloys of steel, etc.) and may be formed (e.g.,cast, forged or otherwise machined) according to conventionalapproaches. The shank 4 and multi-wall blade 6 may be integrally formed(e.g., cast, forged, three-dimensionally printed, etc.), or may beformed as separate components which are subsequently joined (e.g., viawelding, brazing, bonding or other coupling mechanism).

FIG. 2 is a cross-sectional view of the multi-wall blade 6 taken alongline A-A of FIG. 1. As shown, the multi-wall blade 6 may include, forexample, an arrangement 30 of cooling channels including a plurality ofhigh effectiveness near wall cooling channels 18 and one or more lowcooling effectiveness internal channels 20, hereafter referred to as“central plenums.” Various cooling circuits can be provided usingdifferent combinations of the near wall cooling channels 18 and centralplenums 20.

An embodiment including a two-pass serpentine cooling circuit 40 isdepicted in FIG. 3, which is a cross-sectional view of the multi-wallblade 6 taken along line B-B of FIG. 1. The two-pass serpentine coolingcircuit 40 is located radially outward along the multi-wall blade 6(e.g., closer to the tip area 12 of the multi-wall blade 6) relative tothe arrangement 30 of cooling channels shown in FIG. 2. To this extent,comparing FIGS. 2 and 3, the two-pass serpentine cooling circuit 40effectively “shields” the central plenums 20 and at least some of thenear wall cooling channels 18 from the very high heat loads thattypically occur at the tip area 12 of the multi-wall blade 6 duringrotation of the multi-wall blade 6 (e.g., in a gas turbine).

The two-pass serpentine cooling circuit 40 includes a first leg 42 thatextends over and at least partially covers the central plenums 20. Thefirst leg 42 extends rearward from a forward air feed cavity 44 towardthe trailing edge 16 of the multi-wall blade 6. Although shown in FIG. 3as extending over all of the central plenums 20, the first leg 42 of thetwo-pass serpentine cooling circuit 40 may, in general, extend over oneor more of the central plenums 20.

The two-pass serpentine cooling circuit 40 further includes a second leg46 that extends over and at least partially covers a set (e.g., one ormore) of the near wall cooling channels 18 disposed adjacent thepressure side 8 of the multi-wall blade 6. A turn 45 disposed adjacentthe trailing edge 16 of the multi-wall blade 6 fluidly couples the firstand second legs 42, 46 of the two-pass serpentine cooling circuit 40.The second leg 46 extends from the turn 45 toward the leading edge 14 ofthe multi-wall blade 6. Comparing FIGS. 2 and 3, it can be seen that inthis embodiment the second leg 46 extends over all of the near wallcooling channels 18 disposed adjacent the pressure side 8 of themulti-wall blade 6. In general, however, the second leg 46 of thetwo-pass serpentine cooling circuit 40 may extend over one or more ofthe near wall cooling channels 18 disposed adjacent the pressure side 8of the multi-wall blade 6.

Cooling air is supplied to the first leg 42 of the two-pass serpentinecooling circuit 40 via the air feed cavity 44. The air feed cavity 44may be fluidly coupled to, and receive cooling air from, at least one ofthe central plenums 20. In other embodiments, the air feed cavity 44 maybe fluidly coupled to, and receive cooling air from, at least one of thenear wall cooling channels 18. In either case, in this embodiment, theair feed cavity 44 is disposed near the leading edge 14 of themulti-wall blade 6.

In FIG. 3, viewed in conjunction with FIGS. 1 and 2, cooling air flowsfrom the air feed cavity 44 (e.g., out of the page in FIG. 3) into thefirst leg 42, through the turn 45, and into the second leg 46. In thefirst and second legs 42, 46 and the turn 45 of the two-pass serpentinecooling circuit 40, the cooling air absorbs heat (e.g., via convention)from adjacent portions of the tip area 12 of the multi-wall blade 6,shielding the underlying near wall cooling channels 18 and centralplenums 20 from excessive heat. The cooling air flows out of the firstand second legs 42, 46 (e.g., out the page in FIG. 3) via at least onetip film channel 48. Cooling air is directed by the tip film channels 48to the tip 22 of the multi-wall blade 6. The cooling air is exhaustedfrom the tip 22 of the multi-wall blade 6 as tip film 24 to provide tipfilm cooling. In addition, cooling air is exhausted out of the secondleg 46 to the pressure side 8 of the multi-wall blade 6 through at leastone pressure side film channel 50 to provide film 52 for pressure sidefilm cooling.

Cooling air may also be exhausted from at least one of the near wallcooling channels 18 to the tip 22 to provide tip film cooling. Forexample, as shown in FIG. 3, at least one of the near wall coolingchannels 18 adjacent the suction side 10 of the multi-wall blade 6 maybe fluidly coupled to the tip 22 of the multi-wall blade 6 by at leastone tip film channel 54. Cooling air is exhausted (out of the page inFIG. 3) from the tip film channels 54 to provide tip film 24 for tipfilm cooling.

In another embodiment, an aft air feed cavity 144 disposed adjacent thetrailing edge 16 of the multi-wall blade 6 may be used to supply coolingair to the two-pass serpentine cooling circuit 140. Such a configurationis depicted in FIG. 4, viewed in conjunction with FIGS. 1 and 2.

The two-pass serpentine cooling circuit 140 illustrated in FIG. 4includes a first leg 142 that extends over and at least partially coversat least the central plenums 20. The first leg 142 extends forward froman aft air feed cavity 144 toward the leading edge 14 of the multi-wallblade 6. A second leg 146 of the two-pass serpentine cooling circuit 140extends over and at least partially covers a set (e.g., one or more) ofthe near wall cooling channels 18 disposed adjacent the pressure side 8of the multi-wall blade 6. A turn 145 disposed adjacent the leading edge14 of the multi-wall blade 6 fluidly couples the first and second legs142, 146 of the two-pass serpentine cooling circuit 140. The second leg146 extends from the turn 145 toward the trailing edge 16 of themulti-wall blade 6.

The air feed cavity 144 may be fluidly coupled to, and receive coolingair from, at least one of the central plenums 20 or at least one of thenear wall cooling channels 18. As with the embodiment shown in FIG. 3,the two-pass serpentine cooling circuit 140 depicted in FIG. 4 isconfigured to shield the central plenums 20 and at least some of thepressure side near wall cooling channels 18 from the very high heatloads that typically occur at the tip area 12 of the multi-wall blade 6.Further, the two-pass serpentine cooling circuit 140 depicted in FIG. 4is configured to provide tip film 24 and pressure side film 52 for tipfilm cooling and pressure side film cooling, respectively.

In yet another embodiment, as depicted in FIG. 5, viewed in conjunctionwith FIGS. 1 and 2, a first leg 242 of a two-pass serpentine coolingcircuit 240 may be enlarged to extend over and at least partially covernot only the central plenums 20 (e.g., as in FIG. 3), but also a set(e.g., one or more) of the near wall cooling channels 18 disposedadjacent the suction side 10 of the multi-wall blade 6. The first leg242 extends from an air feed cavity 244 toward the trailing edge 16 ofthe multi-wall blade 6. As in the embodiment depicted in FIG. 3, thesecond leg 246 of the two-pass serpentine cooling circuit 240 extendsover and at least partially covers a set (e.g., one or more) of the nearwall cooling channels 18 disposed adjacent the pressure side 8 of themulti-wall blade 6. A turn 245 disposed adjacent the trailing edge 16 ofthe multi-wall blade 6 fluidly couples the first and second legs 242,246 of the two-pass serpentine cooling circuit 240. The second leg 246extends from the turn 245 toward the leading edge 14 of the multi-wallblade 6.

The air feed cavity 244 may be fluidly coupled to, and receive coolingair from, at least one of near wall cooling channels 18 or at least oneof the central plenums 20. The two-pass serpentine cooling circuit 240depicted in FIG. 5 is configured to shield the central plenums 20, atleast some of the suction side near wall cooling channels 18, and atleast some of the pressure side near wall cooling channels 18 from thevery high heat loads that typically occur at the tip area 12 of themulti-wall blade 6. Further, similar to the embodiment shown in FIG. 3,the two-pass serpentine cooling circuit 240 depicted in FIG. 5 isconfigured to provide tip film 24 and pressure side film 52. for tipfilm cooling and pressure side film cooling. respectively.

In FIG. 5, the air feed cavity 244 is disposed near the leading edge 14of the multi-wall blade 6. with the first leg 242 of the two-passserpentine cooling circuit 240 extending toward the trailing edge 16 ofthe multi-wall blade 6. However, similar to the embodiment shown in FIG.4, the air feed cavity 244 may be disposed near the trailing edge 16 ofthe multi-wall blade 6, with the first leg 242 of the two-passserpentine cooling circuit 240 extending toward the trailing edge 16 ofthe multi-wall blade 6.

FIGS. 6-8 depict an illustrative method for forming a portion 60 of thetwo-pass serpentine cooling circuit 40 according to an embodiment. Across-sectional view of a core 62 (e.g., a ceramic core) for use in aprocess for casting the portion 60 of the two-pass serpentine coolingcircuit 40 is shown in FIG. 6.

The core 62 includes a squealer core section 64, a tip core section 66,and at least one body core section 68. Support rods 70 secure andseparate the various core sections 64, 66, 68. The squealer core section64 will form, after casting, a cavity at the tip 22 of the multi-wallblade 6 that is radially open to the outside. The tip core section 66will form, after casting, one of the legs 42, 46 of the two-passserpentine cooling circuit 40. The body core section 68 will form, aftercasting at least one of the near wall cooling channels 18 or centralplenums 20.

An example of a metal casting 80 produced using the core 62 (e.g., usingknown casting techniques) is depicted in FIG. 7. The casting 80 includesa plurality of openings 82 corresponding to the locations of the supportrods 70 in the core 62. According to an embodiment, as shown in FIG. 8,each opening 82 may be sealed using a metal (e.g., braze material) plug84. The plug 84 can, for example, be inserted into an opening 82,press-fit or otherwise inserted into an intra-cavity rib 86 of thecasting 80, and secured (e.g., via brazing) to the floor 88 of thesquealer cavity 90 and the intra-cavity rib 86. To this extent, theplugs 84 extend completely through the opening 92 between theintra-cavity rib 86 and the floor 88 of the squealer cavity 90,preventing cooling air from leaking out of the opening 92 through theopenings 82.

The opening 92 between the intra-cavity rib 86 and the floor 88 of thesquealer cavity 90 may be used, for example, to provide one of the legs42, 46 of the two-pass serpentine cooling circuit 40, with the plugs 84oriented substantially perpendicular to the flow of cooling air (e.g.,into or out of the page in FIG. 8) through the opening 92. In thisposition, the plugs 84 not only seal the openings 82 on opposing sidesof the opening 92, but also serve as cooling pins, increasing thecooling effectiveness of the two-pass serpentine cooling circuit 40 byimproving convective heat flow and promoting turbulent air flow.Possible locations of the plugs 84 in the first and second legs 42, 46of the two-pass serpentine cooling circuit 40 are shown in FIGS. 3-5.The depicted locations of the plugs 84 in FIGS. 3-5 are for illustrationonly and are not meant to be limiting.

FIG. 9 shows a schematic view of gas turbomachine 102 as may be usedherein. The gas turbomachine 102 may include a compressor 104. Thecompressor 104 compresses an incoming flow of air 106. The compressor104 delivers a flow of compressed air 108 to a combustor 110. Thecombustor 110 mixes the flow of compressed air 108 with a pressurizedflow of fuel 112 and ignites the mixture to create a flow of combustiongases 114. Although only a single combustor 110 is shown, the gasturbomachine 102 may include any number of combustors 110. The flow ofcombustion gases 114 is in turn delivered to a turbine 116, whichtypically includes a plurality of turbine buckets 2 (FIG. 1). The flowof combustion gases 114 drives the turbine 116 to produce mechanicalwork. The mechanical work produced in the turbine 116 drives thecompressor 104 via a shaft 118, and may be used to drive an externalload 120, such as an electrical generator and/or the like.

In various embodiments, components described as being “coupled” to oneanother can be joined along one or more interfaces. In some embodiments,these interfaces can include junctions between distinct components, andin other cases, these interfaces can include a solidly and/or integrallyformed interconnection. That is, in some cases, components that are“coupled” to one another can be simultaneously formed to define a singlecontinuous member. However, in other embodiments, these coupledcomponents can be formed as separate members and be subsequently joinedthrough known processes (e.g., fastening, ultrasonic welding, bonding).

When an element or layer is referred to as being “on”, “engaged to”,“connected to” or “coupled to” another element, it may be directly on,engaged, connected or coupled to the other element, or interveningelements may be present. In contrast, when an element is referred to asbeing “directly on,” “directly engaged to”, “directly connected to” or“directly coupled to” another element, there may be no interveningelements or layers present. Other words used to describe therelationship between elements should be interpreted in a like fashion(e.g., “between” versus “directly between,” “adjacent” versus “directlyadjacent,” etc.). As used herein, the term “and/or” includes any and allcombinations of one or more of the associated listed items.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they have structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

What is claimed is:
 1. A cooling system, comprising: a serpentinecooling circuit, the serpentine cooling circuit including a first legextending in a first direction, a second leg extending in a seconddirection, and a turn fluidly coupling the first leg and the second leg;and an air feed cavity for supplying cooling air to the serpentinecooling circuit; wherein the first leg of the serpentine cooling circuitextends radially outward from and at least partially covers at least onecentral plenum of a multi-wall blade, and wherein the second leg of theserpentine cooling circuit extends radially outward from and at leastpartially covers a first set of near wall cooling channels of themulti-wall blade.
 2. The cooling system of claim 1, wherein the firstleg of the serpentine cooling circuit extends from the air feed cavitytoward a trailing edge of the multi-wall blade, and wherein the secondleg of the serpentine cooling circuit extends from the turn toward aleading edge of the multi-wall blade.
 3. The cooling system of claim 1,wherein the first leg of the serpentine cooling circuit extends from theair feed cavity toward a leading edge of the multi-wall blade, andwherein the second leg of the serpentine cooling circuit extends fromthe turn toward a trailing edge of the multi-wall blade.
 4. The coolingsystem of claim 1, wherein the first set of near wall cooling channelsis located adjacent a pressure side of the multi-wall blade.
 5. Thecooling system of claim 1, wherein the first leg of the serpentinecooling circuit extends over and at least partially covers a second setof near wall cooling channels in the multi-wall blade.
 6. The coolingsystem of claim 5, wherein the second set of near wall cooling channelsis located adjacent a suction side of the multi-wall blade.
 7. Thecooling system of claim 1, wherein at least one of the first leg or thesecond leg of the serpentine cooling circuit includes at least one tipfilm channel for directing the cooling air to a tip of the multi-wallblade to provide tip film.
 8. The cooling system of claim 1, wherein thesecond leg of the serpentine cooling circuit includes at least onepressure side film channel for directing the cooling air to a pressureside of the multi-wall blade to provide pressure side film.
 9. Thecooling system of claim 1, wherein the cooling air is supplied to theair feed cavity from a central plenum or a near wall cooling channel ofthe multi-wall blade.
 10. A multi-wall turbine blade, comprising: acooling system disposed within the multi-wall turbine blade, the coolingsystem including: a serpentine cooling circuit, the serpentine coolingcircuit including a first leg extending in a first direction, a secondleg extending in a second direction, and a turn fluidly coupling thefirst leg and the second leg; and an air feed cavity for supplyingcooling air to the serpentine cooling circuit; wherein the first leg ofthe serpentine cooling circuit extends radially outward from and atleast partially covers at least one central plenum of the multi-wallturbine blade, and wherein the second leg of the serpentine coolingcircuit extends radially outward from and at least partially covers afirst set of near wall cooling channels of the multi-wall turbine blade.11. The multi-wall turbine blade of claim 10, wherein the first leg ofthe serpentine cooling circuit extends from the air feed cavity toward atrailing edge of the multi-wall blade, and wherein the second leg of theserpentine cooling circuit extends from the turn toward a leading edgeof the multi-wall blade.
 12. The multi-wall turbine blade of claim 10,wherein the first leg of the serpentine cooling circuit extends from theair feed cavity toward a leading edge of the multi-wall blade, andwherein the second leg of the serpentine cooling circuit extends fromthe turn toward a trailing edge of the multi-wall blade.
 13. Themulti-wall turbine blade of claim 10, wherein the first set of near wallcooling channels is located adjacent a pressure side of the multi-wallblade.
 14. The multi-wall turbine blade of claim 10, wherein the firstleg of the serpentine cooling circuit extends over and at leastpartially covers a second set of near wall cooling channels in themulti-wall blade.
 15. The multi-wall turbine blade of claim 14, whereinthe second set of near wall cooling channels is located adjacent asuction side of the multi-wall blade.
 16. The multi-wall turbine bladeof claim 10, wherein at least one of the first leg or the second leg ofthe serpentine cooling circuit includes at least one tip film channelfor directing the cooling air to a tip of the multi-wall blade toprovide tip film.
 17. The multi-wall turbine blade of claim 10, whereinthe second leg of the serpentine cooling circuit includes at least onepressure side film channel for directing the cooling air to a pressureside of the multi-wall blade to provide pressure side film.
 18. Themulti-wall turbine blade of claim 10, wherein the cooling air issupplied to the air feed cavity from a central plenum or a near wallcooling channel of the multi-wall blade.
 19. The multi-wall turbineblade of claim 10, wherein the multi-wall turbine blade forms a portionof a turbine bucket, and wherein the turbine bucket includes a shankcoupled to the multi-wall turbine blade.
 20. A turbomachine, comprising:a gas turbine system including a compressor component, a combustorcomponent, and a turbine component, the turbine component including aplurality of turbine buckets, and wherein at least one of the turbinebuckets includes a multi-wall blade; and a cooling system disposedwithin the multi-wall blade, the cooling system including: a serpentinecooling circuit, the serpentine cooling circuit including a first legextending in a first direction, a second leg extending in a seconddirection, and a turn fluidly coupling the first leg and the second leg;and an air feed cavity for supplying cooling air to the serpentinecooling circuit; wherein the first leg of the serpentine cooling circuitextends radially outward from and at least partially covers at least onecentral plenum of the multi-wall blade, and wherein the second leg ofthe serpentine cooling circuit extends radially outward from and atleast partially covers a first set of near wall cooling channels of themulti-wall blade.